I am trying to electrospin PAN-DMF 12 wt% solution, needle to plate distance 8.5 cm, 11 kV and flow rate of 0.5 mL/h.
In the beginning, I get a good vertical jet and the spraying happens within my selected area. However, after approximately 2 hours of spinning, the jet starts to spray sideways in a circular manner and droplets start forming. Moreover, it starts spraying outside the selected spinning area.
This has happened 3 times and I am unable to understand the reason for this, and how to avoid this from happening.
Dear Nooruddin
As you stated, the problem appears after 2 hours. The most probable is the conductivity problem.
The conducting flat plate (the negative plate) was covered with fibers decreasing the conductivity, therefore, the jet forwarded to another uncovered space that had a higher conductivity that's why the jet starts to spray sideways in a circular manner.
To solve this problem
Either you increase the applied voltage or use a rotating drum instead of conducting a flat plate
Dear Nooruddin, I agree with Mr. Jamal Babawati point of view. conductivity could be the reason.
Dear Nooruddin Jamali
When a certain amount of nanofiber is collected on the collector, loads are also accumulated in this area. Not all of these loads can be discharged with grounding. Now the loads we call the load remain in the collection area. Residual charges are trying to push the nanofibers into an external space. Accumulation occurs in a larger area. After a while, this is inevitable (e.g. 2 h). The collection area must be changed to prevent this. Either the conveyor-like collector or the roller collector as recommended by Jamal Babawati should be used.
You can find detailed information about the residual charges and your problem in the article below.
Article Charge generation, charge transport, and residual charge in ...
Thanks for your suggestions. Unfortunately I can't use the rotating drum because my collector plate is not flexible and I need to electrospin directly onto the collector plate.
I decided to spin over the entire collector area to have an equal conductivity all over.
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